Impact: Advancing an epidemiological approach to patient safety for inpatient mental health care at the VA is integral to an agenda that uses empirical evidence to ensure that patients with serious mental illness receive care in a safe and therapeutic environment. Background: Reducing adverse events has become a central focus of the health care system over the last two decades both within and outside of the VA. However, patients with mental disorders have been excluded from the major research in this field. Objectives: The current application seeks to 1) Assess the incidence and nature of adverse events that occur within VA medical center inpatient psychiatric units and identify patient characteristics associated with these events; 2) Compare events detected through an epidemiologic record review with those reported to the VHA's adverse event reporting system, to assess the completeness of the information currently available through this system; and 3) Use qualitative methods to understand the mechanisms by which patient, provider, and organizational factors improve or impede patient safety in the VHA system, in order to refine a conceptual model of patient safety in psychiatry. Methods: The study will draw from a national sample of 40 VA psychiatric units and examine 12,000 hospitalizations, with the goal of addressing the objectives of the study by gathering and understanding representative data to inform VA practice and policy.